Tools: GraphicsMagick - Image Processing and Display Package
SDNUM="1033;">
16
2
|
0..65535
|
|
32
|
4
|
0..4294967295
|
The alpha value (if it occurs) represents the degree of pixel
opacity (zero is totally transparent).
PseudoClass images (class=PseudoClass) are
colormapped RGB images. The colormap is stored as a series of
red, green, and blue pixel values. The size of each colormap value
depends on the image depth, as shown in the following table:
|
Depth
|
Bytes Per Value
|
Value Range
|
Bytes Per Colormap Entry
|
|
8
|
1
|
0..255
|
3
|
|
16
|
2
|
0..65535
|
6
|
|
32
|
4
|
0..4294967295
|
12
|
The number of colormap entries is defined by the colors
keyword. The colormap data occurs immediately following the header
(or image directory if the montage keyword is in the header).
Immediately following the colormap data is the PseudoClass
image data. PseudoClass image data is an array of index values
into the color map. The number of bytes comprising the index value
depends on the number of colors in the image. The following
table shows the number of bytes in each colormap index as determined
by the colors keyword:
|
Colors
|
Bytes Per Index
|
Index Range
|
|
<=256
|
1
|
0..255
|
|
<=65535
|
2
|
0..65535
|
|
<=4294967295
|
4
|
0..4294967295
|
If matte is true, each colormap index is immediately
followed by an equally-sized alpha value. The alpha value represents
the degree of pixel opacity (zero is totally transparent).
The image data in a MIFF file may be uncompressed,
runlength encoded, Zip
compressed, or BZip
compressed. The compression keyword in the header defines how
the image data is compressed. Uncompressed pixels are stored one
scanline at a time in row order. Runlength encoded compression counts
runs of identical adjacent pixels and stores the pixels followed by a
length byte (the number of identical pixels minus 1). Zip and BZip
compression compresses each row of an image and precedes the
compressed row with the length of compressed pixel bytes as a word in
most significant byte first order.
MIFF files
may contain more than one image. Simply concatenate each individual
image (composed of a header and image data) into one file.
|
Authors
|
John Cristy,
magick@imagemagick.orgGraphicsMagick
Studio.
|
Copyright
|
Copyright (C) 2002 GraphicsMagick Group
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation files
("GraphicsMagick"), to deal in GraphicsMagick without
restriction, including without limitation the rights to use, copy,
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GraphicsMagick, and to permit persons to whom the GraphicsMagick is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of GraphicsMagick.
The software is provided "as is", without warranty of
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Except as contained in this notice, the
name of the GraphicsMagick Group shall not be used in advertising or
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GraphicsMagick without prior written authorization from the
GraphicsMagick Studio.
Copyright
©
GraphicsMagick Group 2002, 2003, 2004